using System.Net.Http;
using System.Net.Http.StringContent;

//GET

var url = "";

var request = new HttpRequestMessage(RequestUri = new Uri(url));

request.Method = HttpMethod.Get;

var client = new HttpClient();

using (var response = client.SendAsync(request).Result)
{
    response.Content.ReadAsStringAsync().Result;
}

request.Dispose();

// POST

var url = "";

var request = new HttpRequestMessage(RequestUri = new Uri(url));

request.Method = HttpMethod.Post;
var content = new MultipartFormDataContent();
var yourByteData = new byte[];
content.Add(new ByteArrayContent(yourByteData), "name", "filename");
request.Content = content;

var client = new HttpClient();

using (var response = client.SendAsync(request).Result)
{
    response.Content.ReadAsStringAsync().Result;
}

// PUT

var url = "";

var request = new HttpRequestMessage(RequestUri = new Uri(url));

request.Method = HttpMethod.Put;
var content = new StringContent("content", Encoding.UTF8, "application/json");
request.Content = content;

using (var response = client.SendAsync(request).Result)
{
    response.Content.ReadAsStringAsync().Result;
}

// DELETE

var url = "";

var request = new HttpRequestMessage(RequestUri = new Uri(url));

request.Method = HttpMethod.Delete;

using (var response = client.SendAsync(request).Result)
{
    response.Content.ReadAsStringAsync().Result;
}